“Statistical ice cover models were used to project daily mean basin ice cover and annual ice cover duration for Lakes Superior and Erie. Models were
applied to a 1951-80 base period and to three 30-year steady double carbon dioxide (2 X CO,) scenarios produced by the Geophysical Fluid Dynamics Laboratory (GFDL), the Goddard Institute of Space Studies (GISS), and the OregonState University (OSU) general circulation models.”

“Under the three projected 2 X CO, greenhouse warming scenarios ice cover duration is shorter, ice covers are less extensive, and the frequency of winters without ice cover is greater for Lake Erie than for Lake Superior. Under an average 2 X CO, scenario, ice cover is likely to be limited to the shore area and shallows of both lakes.

“The results of our study indicate that the navigation season could be extended to 10 or even 12 months under a 2 x CO, climatic warming. Thus a considerable cost
saving may be associated with reduced Coast Guard and hydropower authority activity and economic benefits may result from increased shipping activity in the winter months. However, the greatly reduced extent and duration of ice cover would likely result in higher evaporation from the Great Lakes and lower lake levels (United States Environmental Protection Agency, 1989). Crowe (1985) indicates that above-freezing air temperature in southern Ontario, Canada will produce less snow cover and a shorter snow cover season. There is a considerable amount of winter recreational activity on ice-covered bays and harbors of the Great Lakes – ice boating, ice fishing, snowmobile racing. Much if not all of this activity would be curtailed or discontinued completely with reduced ice and snow cover. “